Thermo Products chx-3 75n, 100n, 125n operation manual A

All installations and services must be performed by qualified service personnel.

3.THERMOSTAT CONNECTIONS AND ANTICIPATOR SETTING NOTICE: For two-stage thermostat wire connectors see wire diagram page 59.

For single-stage thermostat with two-stage operation connect W from thermostat to W1 on control. W2 on control board is not used. Thermostat dip switches S7-1 & S7-2 on control board (Fig. 21) will need to set at the desired setting per (Table 4B). In this configuration the furnace will light and burn on low fire. If thermostat has not been satisfied in set delay time for second stage the control will step up to high fire until thermostat is satisfied. The auto setting will allow the control to calculate the delay for second stage based on demand. The average calculated duty cycle chart below (Table 4A) shows how the control calculates staging based on demand.

Table 4A

Average
Calculated
Duty Cycle %	or is less	Low to High
Equals	than	Stage Delay	Demand
0	38	12 Min	Light
38	50	10 Min	Light to Average
50	62	7 Min	Average
62	75	5 Min	Average to Heavy
75	88	3 Min	Heavy Light
88	100	1 Min	Heavy

Proper control of the indoor temperature can only be achieved if the thermostat is calibrated to the heating and/or cooling cycle. A vital consideration of this calibration is related to the thermostat heat anticipator.

The proper thermostat heat anticipator setting is 0.4 AMPS for furnace operation only. To increase length of cycle, increase setting of heat scale; to decrease length of cycle, decrease setting of heat scale.

Anticipators for the cooling operation are generally pre-set by the thermostat manufacturer and require no adjustment.

Anticipators for the heating operation are of two types, pre-set and adjustable. Those that are pre-set will not have an adjustment scale and are generally marked accordingly.

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